nixos/hardware/audio: fix audio crackling and improve low-latency performance

- Disable Intel HDA power saving to prevent audio crackling/popping
- Add PipeWire low-latency configuration with optimized quantum settings
- Set default sample rate to 48000 Hz for better compatibility

Resolves audio issues caused by aggressive power management and improves
real-time audio performance for music production and gaming.

Author: khaneliman

modules/nixos/hardware/audio/default.nix

@@ -37,6 +37,11 @@ in
       user.extraGroups = [ "audio" ];
     };
 
+    # Disable audio power saving to prevent crackling
+    boot.extraModprobeConfig = ''
+      options snd_hda_intel power_save=0
+    '';
+
     security.rtkit.enable = true;
 
     services = {
@@ -47,6 +52,14 @@ in
         jack.enable = true;
         pulse.enable = true;
         wireplumber.enable = true;
+        extraConfig.pipewire."99-low-latency" = {
+          context.properties = {
+            default.clock.rate = 48000;
+            default.clock.quantum = 512;
+            default.clock.min-quantum = 256;
+            default.clock.max-quantum = 8192;
+          };
+        };
       };
       pulseaudio.enable = mkForce false;
     };

modules/nixos/services/printing/default.nix

@@ -23,7 +23,10 @@ in
         enable = true;
         browsing = true;
 
-        drivers = with pkgs; [ brlaser ];
+        # Use minimal drivers and rely on IPP Everywhere for modern printers
+        drivers = with pkgs; [
+          brlaser # Keep for legacy Brother printers if needed
+        ];
 
         extraConf = ''
           LogLevel warn
@@ -43,6 +46,60 @@ in
 
           # Timeout after cupsd exits if idle (applied only if cupsd runs on-demand - with -l)
           IdleExitTimeout 60
+
+          # Prefer IPP Everywhere for modern driverless printing
+          # This helps reduce reliance on deprecated printer drivers
+          CreateIPPPrinterQueues All
+
+          # Define missing policy limits to silence warnings
+          <Policy default>
+            <Limit Validate-Job Print-Job Print-URI Create-Job Send-Document Send-URI Hold-Job Release-Job Restart-Job Purge-Jobs Set-Job-Attributes Create-Job-Subscription Renew-Subscription Cancel-Subscription Get-Notifications Reprocess-Job Cancel-Current-Job Suspend-Current-Job Resume-Job CUPS-Move-Job CUPS-Get-Document>
+              Require user @SYSTEM
+              Order deny,allow
+            </Limit>
+
+            <Limit Pause-Printer Resume-Printer Enable-Printer Disable-Printer Pause-Printer-After-Current-Job Hold-New-Jobs Release-Held-New-Jobs Deactivate-Printer Activate-Printer Restart-Printer Shutdown-Printer Startup-Printer Promote-Job Schedule-Job-After Cancel-Jobs CUPS-Add-Modify-Printer CUPS-Delete-Printer CUPS-Add-Modify-Class CUPS-Delete-Class CUPS-Set-Default CUPS-Add-Device CUPS-Delete-Device>
+              AuthType Default
+              Require user @SYSTEM
+              Order deny,allow
+            </Limit>
+
+            <Limit Cancel-Job CUPS-Authenticate-Job>
+              Require user @OWNER @SYSTEM
+              Order deny,allow
+            </Limit>
+
+            <Limit All>
+              Order deny,allow
+            </Limit>
+
+            # Add limits for operations that were showing warnings
+            <Limit Validate-Job>
+              Require user @OWNER @SYSTEM
+              Order deny,allow
+            </Limit>
+
+            <Limit Cancel-Jobs>
+              AuthType Default
+              Require user @SYSTEM
+              Order deny,allow
+            </Limit>
+
+            <Limit Cancel-My-Jobs>
+              Require user @OWNER @SYSTEM
+              Order deny,allow
+            </Limit>
+
+            <Limit Close-Job>
+              Require user @OWNER @SYSTEM
+              Order deny,allow
+            </Limit>
+
+            <Limit CUPS-Get-Document>
+              Require user @OWNER @SYSTEM
+              Order deny,allow
+            </Limit>
+          </Policy>
         '';
       };
     };